Introduction
In many documentary productions, there is preliminary discussion about whether to record the original sound with a separate audio recorder or directly onto the camera's audio tracks. Productions often opt for the second solution, as it initially appears more cost-effective and practical. However, using a separate audio recorder during filming offers advantages that significantly impact the quality of the original sound and the overall audio landscape of a film.
It is assumed that at least two channels (e.g., a mono shotgun microphone and a lavalier mic) need to be recorded simultaneously.
Advantages
No Cable or Wireless Connection to the Camera
If sound is recorded directly onto the camera, there would need to be either a wireless connection or a wired connection from the mixer to the camera. For a wireless setup, two transmitters and two receivers would be required for two channels, which would already exceed the cost of a separate recorder.
In principle, a disturbance-free transmission can never be guaranteed with wireless setups. Furthermore, this method does not allow the sound engineer to monitor the signal that ultimately goes onto the camera's audio tracks; only the mixer output can be monitored. This means that quality issues caused by the use of wireless systems (e.g., dropouts, artifacts, etc.) between the mixer and the camera go unnoticed.
While a wired solution eliminates this source of error and usually allows the sound engineer to monitor the camera's headphone output, this method significantly restricts the flexibility, mobility, and movement of both the cameraman and the sound engineer during filming, as they are connected by a cable. This solution is particularly unfeasible in situations with moving cameras (e.g., handheld) and in tight or difficult filming conditions.
Independent Recording Capability for Ambient Sounds and Atmospheres
Without a separate audio recording device, all ambient sounds and atmospheres would need to be recorded onto the camera. This setup often results in the ultimate absence of relevant sounds in post-production.
Use of Stereo Shotgun and Multiple Lavalier Microphones Through More Tracks
Modern recorders offer the ability to discreetly record up to 16 tracks, depending on the model. This creates opportunities, such as recording in stereo (M/S stereo) or even surround sound (dual M/S), while also capturing multiple lavalier microphones on separate tracks without needing to create a final downmix on set. In post-production, this allows for optimal extraction of individual relevant signals. The additional spatial information and the resulting richness and variety of the original sound make stereo or surround recordings in documentary filmmaking appear more authentic, realistic, and ultimately more documentary-like than original sound recorded in mono.
Higher Audio Quality with Separate Recorders
Dedicated audio recorders for separate sound recording typically have far better input preamps and A/D converters than any professional camera. Digital audio is always recorded linearly and uncompressed (e.g., 48 kHz, 24-bit). This means the audio signal is stored in higher quality (less noise, greater dynamic range, no crosstalk).
Is Setting Up Audio Material Really More Work?
Audio recorders today usually record BWAV (Broadcast Wave) files to hard drives or memory cards which can be directly read by common editing systems (Avid, Final Cut Pro, etc.). These files not only contain multi-track digital audio information but also metadata such as naming, comments, and timecode. During filming, a freerun timecode sync using devices like Ambient Lockits allows for logical linking of picture and sound material, which can be automated in the editing room without significant additional time or cost. This also works with semi-professional cameras lacking TC input by using the audio track for the timecode. The process of syncing audio in both Avid and Final Cut Pro now takes just a few minutes.
